[THIS THREAD CONTAINS HEAVY SPOILERS ABOUT THE ILLDAN'S BOOK AND DH STARTING ZONE.]
If you're interested by the subject but don't intend to read the book, I suggest you read this summary. (If you like lore and will play a DH I highly recommend it.)
http://eu.battle.net/forums/en/wow/topic/17610893188
So I have two questions that puzzle me, one related to the book vs DH starting zone, the other one the book vs the animated short.
Book vs Mardum
At the very end of the book, Illidan is supposed to open the path to Argus for his DHs hoping they can cut the head (well, the shoulder...) of the Legion. However as we all know, we start our journey IG in Mardum and right off the bat we're told Illidan sent us here to get Sargeras' Key (iirc). While reading the end of the book, I expected a twist at the end justifying that, like illidan missing a critical part to open a path to Argus etc, but nothing like that.
In the book the journey is planned to Argus, Illidan goes there as a spirit to prepare the arrival... the only shadow is that as Maiev blocks the way for Vandel so the reader doesn't know exactly what happened after Illidan summoned his DHs. This might be the twist I excpected to read.
But then, where is this information about the key coming from as when we are narrated what illidan does it's never mentioned ? Maybe the cinematic in 2 days (I play on EU server...) will answer that ?
Book vs Animated Short
On the short, we see an attack that happens against a Pit Lord, apparently on their world (confirmed on wowpedia, if that counts as confirmation...) and I don't see when it was supposed to have happened.
In the book there is the (formidable ♥) attack against Nathreza that required a LOT of preparation and sacrifices, and the preparation for the portal to Argus. While Illidan prepares the portal to Argus, the opening of the previous is mentioned quite often but never another one is evoked. A theory that an attack on pit lord's world would be easier and/or would have happened before the events of the books but both seem very far fetched : such a world is Legion territory and thus, probably hard to reach, and on the video we see a lot of trained DH which indicates that it's at least, say 1-2 years after Illdan started training them ? (Reminder : in the book Vandel arrives 4 years before BT assault. There are already DH trained so we can assume it started say 1 year before that ?)
Any idea of what / when this attack was ?